Implement CommentVoteRequest and adjust UI

osu.Game/Online/API/Requests/CommentVoteRequest.cs

@@ -0,0 +1,36 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.IO.Network;
+using osu.Game.Online.API.Requests.Responses;
+using System.Net.Http;
+
+namespace osu.Game.Online.API.Requests
+{
+    public class CommentVoteRequest : APIRequest<CommentBundle>
+    {
+        private readonly long id;
+        private readonly CommentVoteAction action;
+
+        public CommentVoteRequest(long id, CommentVoteAction action)
+        {
+            this.id = id;
+            this.action = action;
+        }
+
+        protected override WebRequest CreateWebRequest()
+        {
+            var req = base.CreateWebRequest();
+            req.Method = action == CommentVoteAction.Vote ? HttpMethod.Post : HttpMethod.Delete;
+            return req;
+        }
+
+        protected override string Target => $@"comments/{id}/vote";
+    }
+
+    public enum CommentVoteAction
+    {
+        Vote,
+        UnVote
+    }
+}